Static Dark Fluid Thin Shells in Schwarzschild-de Sitter Spacetimes: Stability and Black Hole Shadows
Fuente:
arXiv
Guardado en:
| Autores principales: | , , |
|---|---|
| Formato: | Preprint |
| Publicado: |
2026
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1866911468696371200 |
|---|---|
| author | Efstratiou, Dimitrios Paraskevas, Evangelos Achilleas Perivolaropoulos, Leandros |
| author_facet | Efstratiou, Dimitrios Paraskevas, Evangelos Achilleas Perivolaropoulos, Leandros |
| contents | We study the existence and radial stability of static, spherically symmetric thin shells separating two Schwarzschild--de Sitter spacetimes with parameters $(m_\pm,Λ_\pm)$. Using the Israel junction formalism and a linear barotropic equation of state $p = λ(σ- σ_1)c^2$, we decouple the sound speed $c_s^2 = λc^2$ from the equilibrium equation-of-state parameter $w_0 \equiv p_0 / (σ_0 c^2)$ and derive the effective potential governing radial dynamics. For observationally motivated parameters, stable configurations with $σ_0>0$ and $0<λ\leq1$ exist only when $m_+/m_- > 1$. Three distinct stability windows emerge, when $λ=1$: $-3/7 \lesssim w_0 \lesssim 1/2$ for $Λ_+ = Λ_-$, $-2/3 \lesssim w_0 \lesssim 1/2$ for $Λ_+ > Λ_-$ and $0 \lesssim w_0 \lesssim 1$ for $Λ_+ < Λ_-$. Positive-pressure shells ($w_0>0$) reside near the photon sphere, whereas negative-pressure shells ($w_0<0$) extend outward, reaching either the cosmological horizon or the static radius. Stability relies on the variation of $w(σ)$ with the surface energy density. Negative pressure (tension) stabilizes the system because the tension increases during expansion. Conversely, positive pressure stabilizes the system because the pressure increases during contraction. Finally, a static, stable, dark, fluid thin shell acts as a gravitational refractive layer that enlarges the black hole's shadow for a distant, static observer outside the shell. The effect depends on the shell radius $R_0$, the background parameters $(m_{\pm}, Λ_{\pm})$, and the equation-of-state. Dark fluid shells can be considered as theoretical toy models that illustrate qualitative effects. Future high-resolution black hole shadow observations could, in principle, use such models to explore how different equations of state might influence observable signatures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2602_22141 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Static Dark Fluid Thin Shells in Schwarzschild-de Sitter Spacetimes: Stability and Black Hole Shadows Efstratiou, Dimitrios Paraskevas, Evangelos Achilleas Perivolaropoulos, Leandros General Relativity and Quantum Cosmology We study the existence and radial stability of static, spherically symmetric thin shells separating two Schwarzschild--de Sitter spacetimes with parameters $(m_\pm,Λ_\pm)$. Using the Israel junction formalism and a linear barotropic equation of state $p = λ(σ- σ_1)c^2$, we decouple the sound speed $c_s^2 = λc^2$ from the equilibrium equation-of-state parameter $w_0 \equiv p_0 / (σ_0 c^2)$ and derive the effective potential governing radial dynamics. For observationally motivated parameters, stable configurations with $σ_0>0$ and $0<λ\leq1$ exist only when $m_+/m_- > 1$. Three distinct stability windows emerge, when $λ=1$: $-3/7 \lesssim w_0 \lesssim 1/2$ for $Λ_+ = Λ_-$, $-2/3 \lesssim w_0 \lesssim 1/2$ for $Λ_+ > Λ_-$ and $0 \lesssim w_0 \lesssim 1$ for $Λ_+ < Λ_-$. Positive-pressure shells ($w_0>0$) reside near the photon sphere, whereas negative-pressure shells ($w_0<0$) extend outward, reaching either the cosmological horizon or the static radius. Stability relies on the variation of $w(σ)$ with the surface energy density. Negative pressure (tension) stabilizes the system because the tension increases during expansion. Conversely, positive pressure stabilizes the system because the pressure increases during contraction. Finally, a static, stable, dark, fluid thin shell acts as a gravitational refractive layer that enlarges the black hole's shadow for a distant, static observer outside the shell. The effect depends on the shell radius $R_0$, the background parameters $(m_{\pm}, Λ_{\pm})$, and the equation-of-state. Dark fluid shells can be considered as theoretical toy models that illustrate qualitative effects. Future high-resolution black hole shadow observations could, in principle, use such models to explore how different equations of state might influence observable signatures. |
| title | Static Dark Fluid Thin Shells in Schwarzschild-de Sitter Spacetimes: Stability and Black Hole Shadows |
| topic | General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2602.22141 |